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cert-extraction.md

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Extracting Windows Server Remote Desktop Certificate

This procedure is useful when running honeypots to support CredSSP (using --auth ssp). It requires Administrative privileges on the target server and the use of Mimikatz, so it assumes that you are able to deactivate the Anti-Virus on the target server.

WARNING: Cloning the certificate of the RDP server does not mean that the certificate will be trusted. Certificate trust requires a signed certificate from a CA that is trusted by the client. This is not likely to be the case in most scenarios. If you want to do that, you are on your own.

Steps

  1. Turn off AV so mimikatz doesn't get flagged. (Or use excluded directory)

  2. Download mimikatz latest release

  3. Go to Start > Run... > certlm.msc (optional)

  4. Identify the valid certificate under Remote Desktop > Certificates and note the thumbprint (optional)

  5. Export the Remote Desktop certificates using Mimikatz:

    privilege::debug
token::elevate
crypto::capi
crypto::certificates /systemstore:LOCAL_MACHINE /store:"Remote Desktop" /export

  6. Convert public key to .pem using openssl:

    openssl x509 -inform DER -outform PEM -in pubkey.der -out pubkey.pem

  7. Remove private key password (password for .pfx is "mimikatz")

    openssl pkcs12 -nodes -in privkey.pfx -out privkey.key

NOTE: If token::elevate doesn't work. Make sure you are running mimikatz as SYSTEM (ie: under psexec -s cmd.exe)

You can now run pyrdp-mitm by specifying -k privkey.key -c pubkey.pem and PyRDP will serve the same certificate as the server. With the certificate and the private key, RDP servers with Network Level Authentication (NLA) enabled can be MITM. Use --auth ssp to do that.